numerous: Ulster, Connacht, N Leinster etc. Ir. Ó Lochlainn, Lochlann, a first name probably meaning Viking. The best-known sept was of Dál gCais (Clare) and the name exists also as MacLoughlin, q.v. GPN.

Very numerous: all areas, especially Donegal-Derry and Ulster generally. Ir. Mac Lochlainn, from a Norse first name. An important sept of the Northern Uí Néill, located in Inishowen (Donegal). Other septs existed elsewhere. Also as Mac Loughlin, q.v. SI.

MacLochlainn:

rare: Donegal etc. Ir.Lang. See Mac Laughlin.

MacLoghlin:

Very rare: Dublin. See Mac Loughlin.

MacLoughlin:

Very numerous: all areas, especially Donegal and Ulster generally; Louth and N Midlands. Ir. Mac Lochlainn, from Norse first name meaning, perhaps, "viking". More usually Mac Laughlin in the North. There were two principal septs: one of the Northern Uí Néill; the other not Mac Loughlin at all but O'Melaghlin, descended from the High-King Maoilsheachlainn and located in Meath. IF.